This research is concerned with the perception of stimulus structure and its processing by normal humans. Stimulus structure involves such things as relations between dimensions or features (including differentiation of dimensions from features), configurational properties, and structure of sequences at stimuli. Information processing is influenced by the nature of the stimulus structure, and the processes affected include stimulus identification, encoding, memorial representation, focussing strategies in recognition, and selective attention. Stimulus materials currently used are all visual, ranging from fairly abstract patterns of dots to more clearly configured line stimuli and on into actual words.